1. Field of the Invention
This invention relates to a coordinate measuring machine for the measurement of workpieces, and more particularly to a coordinate measuring machine with a movable measuring arm that receives at least one interchangeable measuring sensor system; the measuring arm includes a collision protector that is deflectable transversely of the longitudinal axis of the measuring arm when the sensor system collides with an object, and which thereby prevents damage to the sensor system.
2. Discussion of Prior Art
Such coordinate measuring machines have been known in the art for a long time. These measuring machines are usually constructed such that the measuring arm, and thus the measuring sensor system attached to the measuring arm, can be moved in three mutually orthogonal directions, and such that the measurement sensor system has either a mechanical measuring pin or an optical pickup for measuring the workpieces.
Collisions can easily occur due to operating error or deviation of the position of the workpiece to be measured. It is possible that such collisions can damage the measuring sensor system, which is often relatively expensive, or damage can occur to other parts of the coordinate measuring system. As a result, the measuring arm of commercial coordinate measuring machines has been equipped with a collision protector. The collision protector deflected transversely of the longitudinal axis of the measuring arm when the sensor system collided with an object. Additionally, further motion of the coordinate measuring machine was stopped by deflection of the collision protector, preventing damage to the measuring sensor system.
The collision protector of conventional coordinate measuring machines is usually constructed such that the measuring sensor system must meet certain preconditions regarding weight and dimensioning in order to ensure satisfactory operation of the collision protector. However, efforts have been under way to build more flexible coordinate measuring machines that may be used for different tasks. For example, it has been proposed that coordinate measuring machines also be used with milling tools and/or scribing tools for machining. One such application, for example, would be in scribing clay models. In such applications, the measuring sensor system would need to be interchanged with the machining units. Considerably greater torques and forces have to be taken up by the measuring arm to carry-out machining processes. Heretofore, interchanging measuring sensor systems and machining units in coordinate measuring machines with a collision protector of the kind described could only be carried out with large retooling costs or not at all. This was because the collision protector could not accept the torques that can arise with machining units without deflecting.